1. Field of the Invention
The present invention is generally related to a control system for controlling the positions of trim tabs on a marine vessel and, more particularly, to a coordinated trim tab control system that responds to a manually generated vessel trim tab command signal and selects preferred positions for both the port and starboard trim tabs that are chosen as a function of the current trim tab positions and the efficient operation of the marine vessel.
2. Description of the Prior Art
Various types of trim tabs and similar devices are well known to those skilled in the art and have been used to adjust the position and attitude of marine vessel, relative to the body of water on which they are operating, by adjusting the relative positions of the bow and stern and the relative positions of the port side of the vessel to the starboard side of the vessel. Trim tabs are used to lower or raise the bow of a marine vessel, particularly when the marine vessel is operating on plane. Furthermore, trim tabs have been used to adjust the port or starboard list of the marine vessel.
U.S. Pat. No. 5,385,110, which issued to Bennett et al on Jan. 31, 1995, describes a boat trim control and monitor system. The system includes a boat having a hull and a means, such as trim tabs, mounted to the hull for trimming the attitude of the boat as the hull is propelled through the water. The system includes the facility for selectively adjusting the trim tabs to maintain a desired boat attitude under varying load and sea conditions. A sensor is mounted on the boat hull to provide an electrical sensor signal as a function of boat attitude and is connected to electronic control circuitry that is responsive to the sensor signal for determining the attitude of the boat hull. This electronic control circuitry further includes facility for operator setting of a desired boat attitude. The electronic control circuitry is coupled to an operator display for indicating departure of actual boat attitude indicated by the sensor from the boat attitude desired by the operator, and/or to automatic control circuitry for automatically varying trim tab orientation with respect to the boat hull so as to maintain the boat attitude desired by the operator.
U.S. Pat. No. 5,113,780, which issued to Bennett et al on May. 19, 1992, describes an automatic boat trim tab control. The system includes a pair of trim tabs pivotally mounted to the stern of a boat hull, and an engine responsive to application of electrical ignition power for powering the boat through the water. A pair of fluid actuators extend between the hull and the respective trim tabs for selectively and adjustably moving the tabs between full extended and full retracted positions. A fluid drive is responsive to a boat operator for selectively adjusting positions of the trim tabs independently of each other to maintain a desired attitude of the boat hull. Electronic control circuitry is responsive to removal of ignition power from the engine for operating the fluid drive and energizing the actuators for a predetermined time duration so as to move boat trim tabs to the fully retracted position upon removal of ignition power from the engine.
U.S. Pat. No. 5,263,432, which issued to Davis on Nov. 23, 1993,describes an automatic trim tab control for power boats. Adjustment of a power boat""s trim tabs is automated throughout all phases of the operation of the boat. The boat""s speed and/or revolutions of its engine is sensed and used by electronic circuits, including a microprocessor-based circuit, to control prime movers, typically hydraulic pumps, in order to move the trim tabs to their optimal positions. In one embodiment of the invention, the boat speed is sensed by a speedometer. Below a first predetermined speed, the trim tabs are moved fully downward. Above a second predetermined speed, the trim tabs are moved fully upward.
U.S. Pat. No. 5,474,013, which issued to Wittmaier on Dec. 12, 1995,describes a trim tab auto-retract and multiple switching device. In includes a circuit for causing the trim tabs attached to the stern of a hull of a motorized marine vessel to be automatically fully retracted by activating means independently of the boat ignition switch to cause a capacitor in the circuit to discharge. The means can include at least one switch connected between the capacitor and an electrical power source to which the control circuit can be connected such that the means are activated when the switch is opened.
U.S. Pat. No. 5,474,012, which issued to Yamada et al on Dec. 12, 1995, describes an automatic control for trim tabs. Adjustment is made of the position of the marine transportation system including a boat having a drive, a trimmable port tab and a trimmable starboard tab. The operation of the marine transportation system is monitored to provide an output distinguishing boat operation in an on-plane condition and boat operation in an off-plane condition, to provide an output distinguishing boat travel in a straight forward condition and boat travel in a turning condition and to provide an output distinguishing boat operation in a first heel condition in which the boat tilts to port and boat operation in a second heel condition in which the boat tilts to starboard.
U.S. Pat. No. 4,644,893, which issued to Zepp on Feb. 24, 1987, describes a position indicating apparatus for use in a boat leveling system. The boat leveling system has a pair of trim tabs pivotal between a horizontal position and a downwardly incline position. Each trim tab is movable between the horizontal and inclined positions by a separate fluid motor which includes a cylinder, a piston slidably disposed in the cylinder and a rod connected to the piston. The position of each trim tab is indicated by apparatus which includes a linear potentiometer attached to the rod of the associated fluid motor, the potentiometer having a flexible plastic envelope and a pair of normally spaced-apart conductive strips sealed in the envelope, a ball and spring carried by the cylinder for contacting the envelope and forcing the strips into an electrical contact with each other, and a resistance measuring device connected in circuit with the potentiometer and to provide a readout in degrees of the downward angle from horizontal of the trim tab.
U.S. Pat. No. 4,323,027, which issued to Schermerhorn on Apr. 6, 1982, describes a trim tab for a power boat. The inventive trim tab is formed of a single piece of tough, rigid resin providing an integral mounting plate and a lifter extending aft from a bottom region of a power boat transom. A mounting plate is formed flat to fit against the transom. The lifter extends aft from the mounting plate at about a right angle and has a trailing region curving down around a transverse axis aft of the mounting plate and below the lifter. A pair of semi-tubular surfaces incline from an upper region of the mounting plate down to the curved region of the lifter. The lifter also has side edges that extend downwardly and run aft from the transom and has a downwardly extending ridge that runs aft between semi-tubular surfaces.
U.S. Pat. No. 5,215,029 which issued to Davis on Jun. 1, 1993, describes a hydroplaning boat accessory. A permanently fixed metal trim tab for attachment in pair combinations to the aft end of a boat is described. Each trim tab comprises a downwardly extending aft edge. A top surface of each trim tab comprises an aft area which comprises striations which provide an anti-slip surface. The strength, position of attachment to the boat, and anti-slip surface permit use of the trim tab as a step for entry and exit to and from the boat. Each trim tab comprises a flange for attachment to a transom of the boat from connecting points above and below an aftwardly extending substantially flat plate of the trim tab which is an integral part of the flange. The trim tab comprises a uniform cross section which is compatible with fabrication by an extrusion process.
It would be beneficial if a trim tab control means could be provided which coordinates the movement of two or more trim tabs, with consideration to the present position of the trim tabs and further consideration to the efficient operation of the boat, in response to a manually provided command signal which indicates a desire on the part of the marine vessel operator to affect the position of the vessel while operating at planing speeds. It would also be significantly beneficial if the marine vessel operator did not have to individually select the position of the port and starboard trim tabs but, instead, could move simply command a coordinated change in attitude of the vessel.
A preferred embodiment of the present invention provides a coordinated trim tab control method for a marine vessel having port and starboard trim tabs, wherein the method comprises the steps of sensing the port and starboard trim tabs positions, receiving a manually generated vessel trim command signal, determining a preferred coordinated movement of both the port and starboard trim tabs as a function of the manually generated vessel trim command signal in combination with the positions of the port and starboard trim tabs, and then providing port and starboard trim tab output signals to the trim tabs actuators to achieve the preferred coordinated movement.
In a preferred embodiment of the present invention, the determining step comprises the steps of comparing the port trim tab position to a predetermined maximum range of movement of the port trim tab, comparing the starboard trim tab position to a predetermined maximum range of movement of the starboard trim tab, and then determining a preferred magnitude of coordinated movement of both port and starboard trim tabs as a function of the manually generated vessel trim tab command signal and the relationships of the positions of both the port and starboard trim tabs to their respective maximum ranges of movement.
In a preferred embodiment of the present invention, the manually generated vessel trim command signal is a manually selected one of a plurality of commands comprising a xe2x80x9craise bow relative to sternxe2x80x9d command, a xe2x80x9clower bow relative to sternxe2x80x9d command, a xe2x80x9craise the port side of the vessel relative to the starboard side of the vesselxe2x80x9d command, and a xe2x80x9craise the starboard side of the vessel relative to the port side of the vesselxe2x80x9d command. The manually generated vessel trim common signal can be received from a track pad component comprising four individual switches. The track pad component can comprise a first switch to raise the bow, a second switch lower the bow, a third switch to raise the port side of the vessel relative to the starboard side of the vessel, and a fourth switch to raise the starboard side of the vessel relative to the port side of the vessel.
The determining step of the present invention can comprise a step of minimizing the magnitude of actuation of both port and starboard trim tabs to minimize the drag on the vessel while determining a preferred magnitude of movement of the port and starboard trim tabs. In other words, the control unit of the present invention can determine the most efficient positions of the port and starboard trim tabs that will satisfy the command received from the vessel operator. In most situations, this most efficient position of each trim tab is a position in which the trim tabs are least extended into the water behind the vessel and most fully retracted from that extended position.